Ignition composition



Ga. 10, 1939. L. A. BURROWS HAL 2,175,249

IGNITION COMPOSITION Filed 001;. 28, 1937 L 61408012 A flaw/"04w Wf/l/amf". ff/bezv INVENTOR- ATTORNEY Patented Get. 1% Il3 PIE IGNITIONCOMPOSITION Application October 28; 1937, Serial No. 171,512

.16 Claims.

This invention relates to new and improved ignition compositions adaptedfor eflicient use in blasting initiators and particularly in electricblasting initiators.

An ignition composition to meet the commercial requirementssatisfactorily in electric blasting caps and other initiators mustpossess certain characteristics and properties. It is essential, forexample, that it be capable of ready ignition on application of the heatfrom the passage of an electric current through a fine, highlyresistantwire in contact with the material. Not only must ignition be possible,but it must take place with the use of a low firing current. In the caseof initiators where ignition is brought about by means of the spit froma fuse, such ignition must be certain also. The composition must besufficiently stable so that its ability to ignite is a constant propertynot affected by storage even under unfavorable conditions. In additionto ready ignitibility by the initiating means, a composition to besatisfactory must be capable of giving off suificient heat and flame onignition or of initiating a shock impulse sufficient to bring about thefiring of an adjacent main explosive charge.

While many compositions have been proposed for such use in electricblasting caps and other initiators, no one of them has been entirelysatisfactory in every respect.

An object of the present invention is the production of improvedignition agents. A further object is the preparation of ignition agentssuitable for use in electric blasting caps and other blastinginitiators. preparation of new chemical compounds of a desirable degreeof sensitiveness and suited for use in the manner described. Additionalobjects will be disclosed as the invention is described more fullyhereinafter.

We have found that the foregoing objects are accomplished by thepreparation of an ignition agent comprising a complex or double salt oflead nitrate with a lead salt of a nitrophenol. These salts aresometimes found to be hydrated salts, containing water ofcrystallization. The his basic double salts are the ones preferablyused. The lead salts of various nitrophenols are adapted for use in thismanner; for example, the salts of dinitrocresols, dinitrophenols,trinitrophenol, and the like. Preferably we make use of the double saltof 4,6-dinitro-ortho-cresol which may be designated more exactly as3,5-dinitro-2- hydroxy-l-methyl benzene. Wherever we may hereafter referin this application to 4,6-dinitro- A still further object is the Iortlio-cresol, it will be understood that this is identical with3,5-dlnitro-2-hydroxy-l-methyl benzene. Our preferred complex salt ofdinitroortho-cresol may be designated as lead nitratehis basiclead-4,6-dinitro-ortho-cresylate mono- As examples of methods ofpreparing the complex. salts in accordance with our-invention, thefollowing will serve:

EXAMPLE 1.Lead nitrato-bis-basic lead- 4,fi-dinitro-ortho-cresylatemonohyclrate A solution of 95.1 gms. oi 4,6-dinitro-orthocresol in 2250cc. of water, containing 57.6 gms. of sodium hydroxide, was added in asmall, steady stream over 27 minutes to a solution of 348 gms. of leadnitrate in 6000 cc. of water maintained at 60 to 61 C. After theaddition, stirring was continued While the suspension was cooled t roomtemperature by a cold water bath. The supernatant liquid was decantedand the crystalline solid washed once by decantation with 300 cc. ofcold water and twice by stirring with 350 cc. of cold water andfiltering. The orange colored crystalline product was air-dried at '70to 75 C. A weight of 335.9 gins, of product was obtained, containing58.69% lead and 1.81% nitrate nitrogen. That this product was amonohydrate is indicated by the fact that the loss in weight in vacuo at150 C. amounted to 1.3% as against 1.26% for the theoretical amount ofwater in the monohydrate.

EXAMPLE 2.-Lead nitrato-bis basic lead pz'crate A solution of 18.32 gms.of picric acid in 400 cc. of water containing 9.6 gms. of sodiumhydroxide, was added dropwise during 30 minutes to a well stirringsolution of 55.6 gms. of lead nitrate in 1000 cc. of water maintained at70 to 72 C. After all had been added, the suspension was cooled to roomtemperature, filtered, Washed once by decantation and twice by agitatingwith cold water and filtering. The air-dried product 58.2 gms.

Example d.-Lead nitmto bis basic Zeud-2,d=dinitrophenolate A solution of14.172, guns. of ZA-dinitrophenol in 400 cc. of Water, containing 9.6gms. of sodium hydroxide, was added dropwise during minutes to awell-agitated solution of 58 gms. of lead nitrate in 1000 cc. of watermaintained at 70 to 72 C. After the addition, the mixture was stirredand heated to 80 C. for minutes. The solution was then cooled andfiltered. The precipitate was washed once by decantation and twice bystirring with 100 cc. of cold water and filtering. The crystals weredried by washing on the filter with acetone and consisted of brightyellow needles weighing 46.? gms. The product ments.

contained 58.91%. lead and 1.5% nitrate nitrogen.

The foregoing examples show methods of preparing complex lead salts ofnitrophenols and lead nitrate for use in accordance with our invention.It will be understood that many other salts may be applied successfullyalso, and that the method of procedure may be varied considerably. Theexamples given are by way of illustration only.

While the above complex salts may be used by themselves, preferably theywill be admixed with other materials; for example, oxidizing agents suchas potassium chlorate, barium peroxide, calcium peroxide, and the like,and agents giving off heat and sparks, such as finely-divided Complexlead salt ofl 2 3 I Percent Percent Percent 4, 6-dll1ltl001fl10-0!8$0180 70 Zirconium 20 15 Potassium chlorate. 20 15 All three of theforegoing compositions, when included as charges in electric blastingcaps, are readily ignited by the heat of an incandescent bridge wire,and have low firing current require- Moreover, all are less sensitive toshock than mercury fulminate, and throw out hot igniting flames. It willbe understood, however, that the sensitiveness to shock as well as toelectro-static efiects will depend on the nitrophenol used, the doublesalts of the trinitro-compounds being more sensitive in gneralthan thoseof the dinitro-compounds. Not only are the above compositions of adesirable range of properties when prepared, but these properties remainconstant on storage. For example, the compositions shown have beenstored for six months at a temperature of F. and have been found toundergo no appreciable change during such heated storage.

It will be understood that the compositions described, containing ournew complex salts, may be used as ignition compositions under varyingconditions. For example, they may be employed as cap charges forignition by means of fuse, as loose charges in electric blasting caps orelectric squibs, or as. the ignition charge in caps of the so-calledconcave plug type. Preferably, we use the composition containing thelead nitratohis basic lead-4,G-dinitro-ortho-cresylatej as an ignitioncharge in the form of a bead surrounding a bridge wire. A desirablecomposition will arran e comprise more than 50% of the double salt, 5 to3ii% potassium chlorate, and 5 to 30% zirconium. lit has particularadvantage in such use for igniting delay charges in electric blastingcaps because of its ready ignition, low firing current requirements,certain action, and be" cause of the hot flame given off on ignition.

In order to disclose this latter preferred embodiment of our inventionmore fully, reference is made to the accompanying drawing. It is to beunderstood, however, that this is to be taken solely by way ofillustrationand is not to be regarded as a limitation upon the scope ofour invention which has many important applications other than thoseherein particularly illustrated.

Referring generally to the drawing, the sole figure represents avertical section of an electric blasting initiator of the delay typeprovided with the specialbridge plug bead type of ignition.

In particular, the electric blasting initiator comprises the rigid shellI, suitably of metal; in the base of the shell is placed a base charge2, of either detonating or deflagrating material, depending on whether asquib or a cap is desired. Superimposed onthe base charge is anintermediate charge capable of initiating said base I charge. Above saidintermediate charge 3 and in firing relation therewith, is placed thedelay eley ment comprising the metal carrier 4, which contains the delaycomposition 5, preferably of the type which burns substantially withoutthe evolution of gas. The delay element is, in turn, in firing relationwith the electrical ignition means above'it through the chamber 6 topermit the expansion and cooling of the gases. The electrical ignitionmeans above this chamber comprises the bridge plug 1, through which arepassed the leading wires 8 and 9, the ends of which are brought intoelectrical connection by means of the high resistance bridge wire ID.The ignition composition according to our invention is fixed on thebridge wire in the form of the compact bead H, which bead is preferablysuspended thereon without the aid of additional support. Closure iseffected by means of the waterproofing layer l2 and the sealing layerl3. v

While our invention has been described in detail in the forgoing, itwill be understood that many variations may be made from thecompositions shown and the details of preparation and use, withoutdeparting from the spirit of the invention. We wish to be limited onlyby the following patent claims.

We claim:

1. A chemical compound consisting of a complex salt of lead nitrate witha lead salt of a nitrophenol.

2. A chemical compound consisting of a complex salt .of lead nitratewith a basic lead salt of a nitrophenol.

3. A chemical compound consisting of a complex salt of lead nitrate with2. bis basic lead salt of a nitrophenol. I

4. A chemical compound consisting of a complex salt of lead nitrate witha his basic lead dinitrophenolate.

5. A chemical compound consisting of a complex salt of lead nitrate witha bis basiclead picrate.

6. A chemical compound consisting of a complex salt of lead nitrate witha his basic lead dinitro-ortho-cresylate.

7. A chemical compound consisting of a complex salt of lead nitrate witha his basic lead salt of 4,6-dinitro-ortho-cresol.

8. An ignition agent comprising a complex salt of lead nitrate with alead salt of a nitrophenol.

9. An ignition agent comprising a complex salt of lead nitrate with abasic lead salt of a nitrophenol.

10. An ignition agent comprising a complex salt of lead nitrate with ahis basic lead salt of a nitrophenol.

11. An ignition agent comprising a complex salt of lead nitrate with 2.bis basic lead dinitrophenolate.

12. An ignition agent comprising a complex salt of lead nitrate with abis basic lead picrate.

13. An ignition agent comprising a complex salt 15 of lead nitrate witha bis basic lead dinitro-orthocresylate.

14. An ignition agent comprising a complex salt of lead nitrate with ahis basic lead salt of 4,6- dinitro-ortho-cresol. 15. An ignitioncomposition comprising 5 to 30% potassium chlorate, 5 to 30% zirconium,and more than 50% of a double salt of lead nitrate with 2. bis basiclead 'salt of 4,6-dinitroortho-cresol.

16. In an electric blasting initiator of the delay type, anignitioncharge in the form of a bead surrounding the bridge wire, which chargecomprises a. complex salt of lead nitrate with a lead salt of anitrophenol.

LAWTON ARTHUR BURROWS. WILLIAM FREDERICK FILBERT.

